1. Field of the Invention
The present invention relates generally to an agricultural implement including a folding toolbar. More particularly, the present invention relates to an improved method and apparatus for providing stability for the folding toolbar as well as flexibility when operating on uneven terrain.
2. Background Art
As farm implements are made to cover greater areas in a single pass, components of those implements become longer and, thus, exhibit greater tendencies to flex, twist, and generally deform. Incorporating appropriate flexibility of farm implement frames—to conform to uneven terrain—while maintaining adequate stability—that is, resist flexing, twisting, and deforming—are challenges faced by implement designers.
Many types of agricultural implements include folding toolbars, including, but not limited to, agricultural wheel rakes. The folding toolbars may be supported at an end farthest from a tongue by a ground engaging wheel or wheels, such as that shown in FIGS. 2a and 2b. Due to the distance between the ground engaging wheel and the rear end of the toolbar, impulses to the ground engaging wheel because of uneven ground and obstacles can result in damage to the toolbar and other parts of the implement.
In the past, the ground engaging wheel attached to the toolbar has been mounted on the side of the toolbar away from the tongue of the implement as seen in FIG. 1. The width of the implement when folded for transport is greater due to the location of the ground engaging wheel. Other choices of location, while narrowing the folded implement have proved untenable because of interference between the ground engaging wheel and other moving parts of the implement.
An improvement to the former problem—that of impulses to the ground engaging wheel 10—can be made by increasing the diameter of the ground engaging wheel. However, it has been found, increasing the diameter of the ground engaging wheel requires an increase in an offset 240, which is the horizontal distance between a substantially vertical axis 230 and a substantially horizontal axis 220 as seen in FIG. 2a. If the offset 240 is not increased with tire diameter, instability results, with a symptom of shimmy. The combination of the increased wheel diameter and the requisite increased offset 240 results in a much greater clearance requirement. The ground engaging wheel must be disposed adequately far from the parts of the implement with which the wheel may interfere.
Forces due to obstructions in the path of the ground engaging wheel, as well as forces due to operating the implement in the field, can result in deformations of the folding toolbar. Prior art implements have utilized joints with limited degrees of freedom to provide rigidity to resist these deformations. However, the joints with limited degrees of freedom have not permitted the folding toolbars to adequately conform to uneven terrain.
The must be foldable between a transport configuration, sufficiently narrow to pass through a gate or traverse public roadways, and a broadened operating configuration. It is also desirable to provide varying windrow widths.
Most folding wheel rakes on the market today that fold by changing the tongue length, do so by using folding arms or telescoping frame members. This causes the working or operational length to be unnecessarily longer, making it more difficult for the operator to turn the tractor and rake at the end of each windrow.
There is, therefore, a need for an agricultural implement including a folding toolbar having ground engaging wheels at outboard ends of the toolbars mounted so as to reduce the folded width of the implement. There is an additional need for the ground engaging wheel to reduce impulse on the toolbar due to uneven ground or obstacles. There is also a need for a folding toolbar providing both conformability to uneven field surfaces and stability under the influence of the loads realized in use of the implement. There is a further need for a folding toolbar wherein the overall length of the implement remains short. There is also a need for a folding toolbar on a wheel rake providing for varying windrow widths.